1. Area of the Art
The invention relates generally to methods of measuring an analyte contained in a body fluid and specifically to minimally invasive methods for measuring analytes, particularly glucose contained in an interstitial fluid of a body.
2. Description of the Prior Art
Treatment of diabetes requires frequent measurement of tissue glucose concentration. This is commonly accomplished by drawing a small blood sample (as by a fingerstick) several times daily. A patient typically uses a lancet to draw a droplet of blood and applies the droplet to a reagent strip which is read in a small meter. Obviously, the process is painful, invasive, time-consuming, and generally unpleasant.
Extensive efforts have been made to measure blood glucose non-invasively. However, proposed non-invasive methods, to date, rely on intensive signal massaging to extract a glucose signature from an overwhelming background. Therefore, it appears very difficult to provide a non-invasive measurement with the required specificity, accuracy, and precision.
The methods provided by the present invention provide a compromise between the conventional fingerstick techniques and the prospective non-invasive techniques. Methods of the present invention are able to preserve the diagnostic performance of more intrusive measurements without drawing samples but do require periodic replacement of passive implanted sensors.
It is an object of the present invention to develop an in vivo glucose measurement method that is as non-invasive as possible. It is also an object of the present invention to provide anin vivo glucose measurement that meets the clinically required specificity, accuracy, and precision. Accordingly, the present invention provides a method for detecting an analyte contained in the interstitial fluid of a body. The method comprises the steps of:
(a) providing at least one sensor particle capable of generating a detectable analyte signal in responding to the analyte concentration in the body,
(b) placing the sensor particle into the skin of the body for allowing the sensor particle to be in contact with the interstitial fluid of the body to generate a detectable analyte signal,
(c) detecting the generated analyte signal, and
(d) determining the concentration of the analyte contained in the interstitial fluid.
Methods of the present invention may be used to measure the glucose concentration of the interstitial fluid in a human as a surrogate measurement for blood glucose. Preferably, the sensor particles are also capable of generating a detectable reference signal for background corrections.
In one embodiment of the present invention, the sensor particles comprise a receptor with a signal fluor. The receptor preferentially recognizes the target analyte, and the binding of the receptor to the analyte allows the signal fluor to generate a detectable analyte signal that is responsive to the concentration of the analyte. A reference fluor may be present in the sensor particles.
Methods of the present invention are less intrusive than the conventional fingerstick technique for measuring blood glucose. They only require periodical replacement of the sensor particles in the skin. In addition, since the sensor particles are in contact with the analytes, relatively specific chemical interactions may be used. The present invention therefore provides better performance than the proposed non-invasive methods for measuring blood glucose. The non-invasive methods rely on intensive signal massaging to extract a glucose signature from an overwhelming background.
The invention is defined in its fullest scope in the appended claims and is described below in its preferred embodiments.